We introduced generators the first time in Extensions 1.2. Those early generators, while useful at times, were quite inflexible and too specific.
In the latest version of Extensions (which came out yesterday!), we introduced the completely redesigned generators. A generator, if you don’t know the concept as we use it, is simply a class that has a Next method that always gives you an object of a certain type. They work a bit like random generators, except the elements may or may not be random. They support various LINQ-like methods, and so also resemble sequences (although generators are always infinite).